Method for producing semiconductor device and photodetector device

ABSTRACT

A large-area semiconductor device formed by adhering substrates, which is free from damages on the elements provided on each substrate during transportation thereof, also free from loss in the production yield and the uniformity of performance, thereby achieving a low cost and a high quality, can be realized by carrying out full-cutting in a substantially vertical direction of each substrate at an end surface on a side of the substrates to be mutually opposed to one another to detach an unnecessary portion, carrying out half-cutting on at least one end surface on a side other than the side to be opposed to merely form a groove between an unnecessary portion and the substrate to leave the unnecessary portion in a connected state, and arranging thus cut substrates so that the full-cutting end surfaces thereof are mutually opposed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of producing a semiconductordevice or a photodetector device by adhering a plurality ofsemiconductor substrates in a planar manner, and more particularly to amethod of producing a semiconductor device having a plurality ofsemiconductor elements over a large area, a one- or two-dimensionalimage reading device adapted for use in a facsimile, a digital copyingapparatus or a scanner, and a photodetector device for converting aradiation such as X-ray or gamma-ray into visible light or the like by afluorescent plate and reading thus converted light.

2. Related Background Art

The amorphous silicon (hereinafter abbreviated as "a-Si") has beenconventionally utilized as the semiconductor material for a large-areasemiconductor device or as the photoelectric converting semiconductormaterial for a photodetecting device such as a sensor array. Inparticular, such film can be easily formed on a large-area glass plateand further it can be used not only as the photoelectric convertingmaterial but also as the semiconductor material for the switching TFT(thin film transistor). It is also widely employed as the semiconductormaterial for the sensor array, since the semiconductor layer of thephotoelectric converting elements and the semiconductor layer of theswitching TFT can be simultaneously formed.

As a typical example of the sensor array employing such a-Si film, therewill be explained the constitution of a sensor array in which a PIN typephotoelectric converting element is combined with an inverse staggeredTFT constituting a switching TFT as a part of the control unit.

FIG. 1 is a schematic plan view of such a sensor array. In FIG. 1,numeral 101 indicates a PIN type photosensor; 102 a switching TFT; 103 adata line; 104 a gate line; and 105 a bias line. Each pixel is composedof a sensor portion and a switching TFT portion, wherein eachphotosensor is connected to each switching TFT which is connected to thedata line 103.

FIG. 2 is a schematic cross-sectional view of one of the pixels shown inFIG. 1. In FIG. 2, numeral 101 indicates a PIN type photosensor; 102 aswitching TFT; 201 a glass substrate; 202 a Cr gate electrode; 203 a SiN(silicon nitride) gate insulation film; 204 an i-type a-Si film; 205 aSiN channel protective film; 206 an n⁺ -type a-Si film; 207 an Al S-Delectrode; 210, 211, 212 p-, i- and n-type a-Si films, respectively; 208a Cr electrode; 209 an ITO electrode; 213 a SiN interlayer insulationfilm; and 214 a protective film.

In the following there will be briefly explained a radiation imagepickup device as an example of the photodetector device utilizing theabove-described sensor array substrate. FIG. 3 shows a schematiccross-sectional view of the structure of such a device.

As shown in FIG. 3, the radiation image pickup device is composed, forexample, of a sensor array 301; a base member 308 serving to support thesensor array and to function as a shield against the radiation; anadhesive 309 for connecting the sensor array 301 and the base member308; a fluorescent member 302 functioning as a wavelength convertingmember for converting the radiation into light to which the sensor arrayis sensitive; a processing circuit board 303 for processing electricalsignals obtained from the sensor array; an IC 307 for driving the sensorarray and the processing circuit; and a flexible wiring 304 forconnecting the processing circuit board with the sensor array. Thesecomponents are fixed by a frame 305 constituting the outer frame of theradiation image pickup device. The radiation enters from a directionindicated by an arrow 310. Such structure realizes a light and thinradiation image pickup device of a large size.

Lower cost, higher performance and larger area are currently beingdemanded for such photodetector devices, but such demands have not beenmet because of various problems which are yet to be solved. Theseproblems will be explained in the following.

Firstly, for realizing a larger area, particularly a size in excess of400×400 mm, there are required a capital investment on the large-sizedmanufacturing facility for matching the large substrate size andautomation of each equipment constituting such facility and thesubstrate transportation therein. This leads to an increase in theproduct cost.

Secondly, in case of producing a large array substrate such as thetwo-dimensional sensor, the increase of the substrate size results inthe decrease of a manufacturing yield, leading to the increase of theproduct cost.

Thirdly, the increase of the area deteriorates the uniformity of deviceproperties, and the uneven distribution of the properties within thepanel (substrate) deteriorates the product quality.

Though these problems are associated with the increase of size, there isdesired a large-sized semiconductor device or photodetector device of alower cost and a higher performance.

SUMMARY OF THE INVENTION

An object of the present invention is to realize a large-sizedphotodetector device of a low cost and a high performance, which doesnot strongly necessitate a manufacturing facility for matching a largesubstrate size and which does not result in an increase of cost and isnot associated with loss in manufacturing yield or in the uniformity ofperformance resulting from the increase of the substrate area.

An object of the present invention is to provide a method of producing asemiconductor device comprising a large-sized panel on which a pluralityof semiconductor substrates are adjacently arranged in a planar manner,at least one of the sides of a semiconductor substrate is formed bycutting, which method comprises the steps: forming a plurality ofsemiconductor substrates by cutting so that an opposite side of each ofthe semiconductor substrates to be adjacently arranged is formed bysubstantially vertical full-cutting to remove an unnecessary portion andso that an end surface of the semiconductor substrate other than theopposite side has a groove merely formed by half-cutting between thesemiconductor substrate and the unnecessary portion to leave anunnecessary portion; handling the semiconductor substrate by holding theleft unnecessary portion; removing the unnecessary portion by snappingoff the unnecessary portion; and arranging the semiconductor substratesso as to be adjacent to one another while the full-cutting sides thereofare mutually opposed.

Another object of the present invention is to provide a method ofproducing a photosensor device comprising a plurality of sensor arraysubstrates, each having a plurality of pixels each composed of aphotoelectric converting element and a switch, and a base member forsupporting the plurality of sensor array substrates so as to beadjacently arranged, which the method comprises the steps of: formingthe sensor array substrate by cutting so that an opposite side of thesensor array substrate to be adjacently arranged is formed bysubstantially vertical full-cutting to remove an unnecessary portion andso that an end surface of sensor array substrate other than the oppositeside has a groove merely formed by half-cutting between the sensor arraysubstrate and the unnecessary portion to leave the unnecessary portion;handling the sensor array substrate by holding the left unnecessaryportion; removing the left unnecessary portion by snapping off suchunnecessary portion; and arranging the sensor array substrates so as tobe adjacent to one another while the full-cutting sides thereof aremutually opposed.

Still another object of the present invention is to provide a method ofproducing a semiconductor device comprising a plurality of substrateseach having a plurality of semiconductor elements, at least one of thesides of each of the substrates being mutually arranged so as to beadjacent to one another, which method comprises the steps of: forming aplurality of substrates by carrying out full-cutting of at least oneside of each of the substrates having a plurality of semiconductorelements; and arranging the substrates so as to be adjacent to oneanother while the full-cutting sides are mutually opposed.

A further object of the present invention is to provide a semiconductordevice comprising a plurality of substrates each having a plurality ofsemiconductor elements, at least one of the sides of each of thesubstrates being arranged so as to be adjacent to one another, whereinan end surface of each of the substrates on at least a side where thesubstrates are mutually opposite to one another has a substantially flatshape and at least one end surface of each of the substrates on at leasta side where the substrates are opposite to one another has an unevenshape.

In the present invention, in the formation of a semiconductor substrate(including a form such as an insulating substrate having a thinsemiconductor layer on the whole or a part of a surface thereof) or asensor substrate by cutting and the adjacent arrangement of thesemiconductor substrates or sensor substrates mutually opposed, theopposite side of each of the substrates is cut by full-cuttingperpendicularly or substantially perpendicularly to the surface of thesubstrate, thereby enabling close arrangement. For the handling of thesubstrates, at least one of the sides thereof other than the oppositeside in the adjacent arrangement is cut by half-cutting to form agrooved portion.

According to the present invention, the gap between the substrates canbe minimized, and the final size of the substrates can be made smallerthan the size in handling by removing an unnecessary portion at thegrooved portion formed by half-cutting.

According to the present invention, a large area device with a low costand a high quality can be achieved by adhering a plurality ofsemiconductor substrates or sensor array substrates onto a base member.

A semiconductor device or a photodetector device of a large area withhigh performance and a low cost can be realized by forming thesemiconductor substrate or the sensor array substrate in a predeterminedsize by cutting in such a manner that an opposite side of thesemiconductor substrate or sensor array substrate to be adjacentlyarranged is cut by substantially vertical full-cutting to remove anunnecessary portion and that an end surface other than the opposite sideis cut by half-cutting to form a groove between the substrate and anunnecessary portion, then by removing the unnecessary portion bysnapping it off at the groove and then by adhering the substrates to thebase member.

Thus, the present invention can easily provide a semiconductor device inwhich a large-sized panel is formed by shaping a plurality ofsemiconductor substrates by cutting and adhering the plurality of cutsemiconductor substrates in a planar manner.

Also the present invention enables handling of the semiconductorsubstrate by holding an unnecessary portion which is left byhalf-cutting on the cut semiconductor substrate. Therefore the handlingof the substrate can be easily achieved without damaging the elementsthereon, for example, by electrostatic charge. Also there can beobtained other advantages such as ease of cleaning after slicing.

Also, since the unnecessary portion is connected to the substrate byhalf-cutting, the unnecessary portion can be easily removing by snappingit off.

In consideration of a certain strength required in the half-cuttingportion and the ease of snapping thereof, the remaining thickness R ofthe half-cutting portion is confirmed to be in a range of 0.2 mm to 0.3mm. The full-cutting means a cutting of the whole thickness as shown inFIG. 5A. The half-cutting means a cutting of a part of the thickness asshown in FIG. 5B.

Also according to the present invention, the full-cutting portions areused as the portion for adjacently arranging the substrates, whereby thegap between the semiconductor substrates or the sensor array substratescan be minimized. Also, since the half-cutting portion is provided atthe external periphery of the adhered panel, it can be formed in an areanot interfering with the image or with the external dimension of thepanel.

Furthermore, by producing a plurality of sensor arrays within alarge-sized substrate and dividing it, it is possible to reduce thelikelihood of defects such as an open circuit or a short circuit withineach divided panel, whereby the overall yield after adhering thesubstrate can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view for showing a part of a photosensorarray;

FIG. 2 is a schematic cross-sectional view for showing one pixel of thephotosensor array shown in FIG. 1;

FIG. 3 is a schematic cross-sectional view for showing a radiationdetecting device employing the photosensor array shown in FIGS. 1 and 2;

FIG. 4 is a schematic plan view for showing an example of the sensorarray substrate prior to cutting;

FIGS. 5A and 12A are schematic cross-sectional views for showingexamples of full-cutting;

FIGS. 5B and 12B are schematic cross-sectional views for showingexamples of half-cutting;

FIG. 6 is a schematic plan view for showing an example of the sensorarray substrate after cutting;

FIG. 7 is a schematic plan view for showing an example of mounting ofthe sensor array substrate;

FIG. 8A is a schematic plan view for showing a close arrangement of aplurality of sensor array substrates;

FIG. 8B is a schematic cross-sectional view taken along the line 8B--8Bin FIG. 8A;

FIG. 9 is a schematic plan view for showing an example of a pixel of thephotosensor array;

FIG. 10 is a schematic cross-sectional view of a pixel shown in FIG. 9;

FIG. 11 is a schematic plan view for showing an example of the sensorarray substrate prior to cutting;

FIG. 13 is a schematic cross-sectional view showing an example of theradiation detecting device;

FIG. 14 is a schematic perspective view of the device shown in FIG. 13;and

FIG. 15 is a schematic perspective view for showing an example of theend surface of the substrate after removal of the unnecessary portionalong the half-cutting portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in detail referring to preferredexamples.

EXAMPLE 1

In Example 1, a large-sized photodetector device having a photoelectricconverting region (light-receiving region) formed by jointing foursensor array substrates and having a size in excess of 400 mm×400 mm wasproduced by the following procedures.

The sensor array substrate was prepared by forming on a glass substrate,PIN type photosensors, switching TFT's, data lines, gate lines, and biaslines. The photosensors were connected to the switching TFT's which wereconnected to data lines.

In the following there will be explained the cutting method for thesensor array substrate and the mounting method therefor. In the presentexample, there will be explained an example of the method of producing aphotodetector device after the preparation of a sensor array of 215mm×215 mm on a glass substrate of 300 mm×250 mm.

FIG. 4 is a schematic plan view of the sensor array substrate prior tocutting the peripheral region. In FIG. 4, numeral 1 indicates a pixelregion, 2 a lead wire region, 3 slicing lines of full-cutting, 4 slicinglines of half-cutting and 5 unnecessary portions.

At first, the desired parts of the sensor array substrate were cut orground using a slicer (manufactured by K & S Co.) provided with adiamond blade (manufactured by Noritake Co.).

The cutting was carried out along the full-cutting slicing lines 3 so asto obtain a substantially vertical full-cutting. Then the grinding wascarried out along the half-cutting slicing lines 4 to form grooves.

FIG. 5A is a schematic cross-sectional view of the full-cutting portiontaken along the line 5A--5A of FIG. 4, while FIG. 5B is a schematiccross-sectional view of the half-cutting portion taken along the line5B--5B of FIG. 4. In the full-cutting portion, the tapering widthbetween the upper cutting width W₁ and the lower cutting width W₂,namely the difference (W₂ -W₁) thereof, is 1.5 μm in average, with astandard deviation of 3.5 μm, wherein a positive tapering is defined aspositive (+) and an inverse tapering is defined as negative (-). Also inthe half-cutting portion, the remaining thickness R of the groove wasselected as 0.2 mm.

FIG. 6 is a schematic plan view of the sensor array substrate after thefull cutting, and it will be understood that the substrate can behandled by the unnecessary portions 5. Consequently the cleaning afterslicing can be facilitated.

Thereafter the unnecessary portions 5 were removed by snapping them off.In consideration of certain necessary strength and ease of snapping, thepreferred remaining thickness R of the half-cutting portion is mostly ina range of 0.2 mm to 0.3 mm, though it is somewhat variable depending onthe material used or the dimension of the substrate.

Subsequently, as shown in FIG. 7, an anisotropically conductive film(not shown in the drawings) was temporarily connected to the sensorarray substrate, and flexible wirings 304 were pressed thereon and fixedwith silicone resin. Then the flexible wirings 304 were soldered to theprocessing circuit substrate.

Thereafter a plurality of sensor array substrates were adhered to thebase member, as shown in a schematic plan view of FIG. 8A. Also FIG. 8Bis a schematic cross-sectional view taken along the line 8B--8B of FIG.8A. As shown in FIG. 8B, a full-cutting portion 83 constituted thejointing portion of the substrates, so that the gap between the sensorarrays could be minimized. On the other hand, the half-cutting portion84 having a protrusion 85 was positioned in the peripheral part of apanel for adhering the substrate and was formed in a range notinterfering with the image or the external dimension.

The photosensor device thus prepared by adhering the plurality of sensorarray substrates adjacently arranged could be produced by theconventional facility even in the ease of having an area exceeding thearea of one substrate producible in the conventional facility, and theproduction yield was significantly improved in comparison with the casethe device was produced with a single substrate, for example a substrateof a size exceeding 400 mm×400 mm. In other words, the division of thesensor array substrate into four decreased the defect percentage in eachsingle substrate, whereby there could be obtained an inexpensivephotosensor device (which is a semiconductor device).

EXAMPLE 2

In this example, an inexpensive sensor array of which manufacturingprocess is simplified by using a same film structure of thephotoelectric converting elements and the switching TFT's was used, anda radiation image pickup device utilizing a photosensor device wasformed by adhering four sensor array substrates in the same manner as inExample 1.

FIG. 9 is a schematic plan view of one pixel of the present example. InFIG. 9, numeral 11 indicates a MIS photoelectric converting elementportion and 12 a switching TFT portion, and FIG. 10 is a schematiccross-sectional view of the pixel shown in FIG. 9. On a glass substrate20, the pixel was composed of an MIS photoelectric converting element 11having a first electrode layer 23, an insulating layer 24, aphotoelectric converting semiconductor layer 25, a layer 26 forpreventing the injection of carriers into the semiconductor layer, and asecond electrode layer 28; and a switching TFT 12 having a firstelectrode layer 22, an insulating layer 24, a semiconductor layer 25, anohmic contact layer 26 to the semiconductor layer, and a secondelectrode layer 29, both being producible by the same and simplifiedprocess.

In the following there will be explained the cutting method for thesensor array substrate and the mounting method therefor. Also in thepresent example, there will be explained the method of producing aradiation image pickup after the preparation of four sensor arrays of100 mm×100 mm on a glass substrate of 300 mm×250 mm.

At first, the sensor array substrate was cut or processed to form agroove formation by using an excimer laser (KrF). FIG. 11 is a schematicplan view of the sensor array substrate. In FIG. 11, numeral 1 indicatesa pixel region, 2 a lead wiring portion, 3 full-cutting slicing lines, 4half-cutting slicing lines and 5 unnecessary portions.

At first the sensor array substrate was cut along the full-cuttingslicing lines 3 in such a manner that the cutting surface wassubstantially perpendicular to the surface of the sensor arraysubstrate. Then grooves were formed along the half-cutting slicing lines4 by cutting.

FIGS. 12A and 12B are schematic cross-sectional views showing afull-cutting portion taken along the line 12A--12A of FIG. 11 and ahalf-cutting portion taken along the line 12B--12B of FIG. 11,respectively. The remaining thickness R of the groove at thehalf-cutting portion was selected as 0.2 mm.

Then the substrate was cleaned by holding the left unnecessary portion 5in the same manner as in Example 1.

Thereafter, the left unnecessary portion 5 was snapped along thehalf-cutting slicing lines 4 to remove the unnecessary portions 5.

Subsequently, an anisotropically conductive film was temporarilyconnected to the sensor array substrate, and flexible wirings werepressed thereon and fixed with silicone resin. Then the flexible wiringswere soldered to the processing circuit substrate.

Thereafter the plurality of sensor array substrates were adhered to thebase member in the same manner as in Example 1, and a fluorescent memberwas adhered with epoxy resin at a side where the radiation enters.

Finally, the adhered sensor array substrates were mounted on the frameof the radiation image pickup device. FIG. 13 is a schematiccross-sectional view thereof. In FIG. 13, a plurality of sensor arraysubstrates 301 were fixed to the base member 308 with the adhesive 309in a simple manner. The radiation image pickup device was composed of afluorescent member 302 for converting the radiation into light to whichthe sensor arrays were sensitive, a processing circuit board 303 forprocessing electrical signals obtained from the sensor arrays, IC's 307provided on the processing circuit board and flexible wirings 304 forconnecting the processing circuit board with the sensor arrays. Thesecomponents were fixed by a frame 305 constituting the outer casing ofthe radiation image pickup device. The radiation enters from a directionindicated by an arrow 310. Such structure realizes a thin andlight-weight radiation image pickup device.

FIG. 14 is a schematic perspective view of such device, in which a partof the frame 305 is omitted for the purpose of clarity, and broken linesindicate the junctions of the sensor array substrates. As explained inthe foregoing, the method of producing the device by preparing aplurality of sensor arrays within the same glass substrate, thendividing the substrate and adhering the divided substrates to therebyimprove the overall yield and achieve a lower cost in comparison withthe method of producing the device by preparing at a time the entiresubstrate having the same size as the base member without dividing thesubstrate.

FIG. 15 shows an example of the end surface of the substrate after theremoval of the unnecessary portion along the half-cutting portion. Asshown in FIG. 15, the obtained end surface from the top portion to amiddle portion in the thickness of the substrate was flat owing to thehalf-cutting, and the uncut portion was a protruding portion remainingalong the elongated direction of the substrate. The end surface of suchprotruding portion is generally uneven as shown in FIG. 15 when theunnecessary portion is removed by snapping it off.

As explained in the foregoing, the present invention facilitateshandling of the substrate, thereby reducing the damage to the panel dueto electrostatic charge or the like because the substrate can be handledby holding the unnecessary portion which is left connected by thehalf-cutting portion.

Also the unnecessary portion left by half-cutting can be easily removedby snapping along the half-cutting portion.

Also in cutting the substrate having the sensor array composed of thephotoelectric converting elements and the switching elements, thefull-cutting and the half-cutting are suitably combined so that thefull-cutting portions constitute the junction portions of the pluralityof sensor array substrates when adhered on the base member, whereby thegap between the sensor arrays can be minimized. Since the half-cuttingportions are positioned in the external periphery portion of the adheredpanels, the half-cutting portions can be formed in a region notinterfering with the image or the external dimension of the panel,thereby realizing a device of a larger size and a lower cost resultingfrom the improved yield of the panel.

Also the method of preparing a plurality of sensor arrays within thesame substrate and then dividing the substrate to reduce the percentageof defects such as open circuit or short circuit within a panel therebyincreases the overall yield.

The present invention is evidently applicable to all the semiconductordevices comprising a large-sized substrate formed by adhering and canprovide similar advantages in all such devices.

In the present invention, the removal of the unnecessary portion by thehalf-cutting portion need not be carried out immediately after thecleaning but can naturally be carried out at any suitable timing. Alsothe half-cutting line may be used for other purposes such as regiondivision, and the removal of a part of the substrate by the half-cuttingline need not be necessarily carried out.

The present invention is not limited to the foregoing examples butencompasses any and all modifications or combinations within the spiritand scope of the present invention.

What is claimed is:
 1. A semiconductor device comprising a plurality ofsubstrates each having a plurality of semiconductor elements, at leastone of sides of each of the substrates being arranged so as to beadjacent to one another, wherein an end surface of each of thesubstrates on at least a side where the substrates are mutually oppositeto one another has a substantially flat shape, and at least one endsurface of each of the substrates on at least a side where the substrateare not opposite to one another has an uneven shape.
 2. A semiconductordevice according to claim 1, wherein the uneven shape comprises aprotruding portion along the longitudinal direction of the end surface.3. A semiconductor device according to claim 2, wherein the end surfaceof the protruding portion has an uneven shape.
 4. A semiconductor deviceaccording to claim 1, wherein said semiconductor element includes a thinfilm transistor.
 5. A semiconductor device according to claim 1, whereinthe semiconductor element comprises a photoelectric converting element.6. A semiconductor device according to claim 5, wherein a thin filmtransistor is provided corresponding to the photoelectric convertingelement, respectively.
 7. A semiconductor device according to claim 5,wherein a wavelength converting member is provided on each of thephotoelectric converting elements.
 8. A semiconductor device accordingto claim 7, wherein the wavelength converting member comprises afluorescent member.
 9. A semiconductor device according to claim 1,wherein the substrates are arranged on a common base member.
 10. Asemiconductor device according to claim 1, wherein the semiconductordevice is a photodetector device.